On Thu, Apr 2, 2009 at 8:01 PM, Jeff Garzik <jeff@garzik.org> wrote:> Linus Torvalds wrote:> The most interesting thing I found: the SSD does 80 MB/s for the first ~1> GB or so, then slows down dramatically. After ~2GB, it is down to 32 MB/s.> After ~4GB, it reaches a steady speed around 23 MB/s.

Isn't that the kernel IO queue, and the dd averaging of transferspeed? For example, once you hit the dirty ratio limit, that is whenit starts writing to disk. So, the first bit you'll see really fastspeeds, as it goes to memory, but it averages out over time to aslower speed. As an example...

Those are with /proc/sys/vm/dirty_bytes set to 1M...echo $((1024*1024*1)) > /proc/sys/vm/dirty_bytesIt's probably better to set it much higher though.--To unsubscribe from this list: send the line "unsubscribe linux-kernel" inthe body of a message to majordomo@vger.kernel.orgMore majordomo info at http://vger.kernel.org/majordomo-info.htmlPlease read the FAQ at http://www.tux.org/lkml/